how do all of you differentiate between, say, fragrance/ aroma/ perfume?

well fragrance and perfume are sweet, aroma can be savory..
(fruits and flowers are fragrant, coffee, and spices are aromatic)

and all three are pleasent.

unlike odor, smell or rank !

Comming throught the garden, each step stirred up the fragrant air, but eventually, as you neared the kitchen, it yeilded to the aroma of coffee and spice cakes, mingled with savory meats cooking. Beyond the garden and kitchen, was the barn rich with a multitude odors and strange smells. Further still, in the field, the air was rank with work of the butchers and now gutted pig.